Psychopaths make up an astounding 1 to 2 percent of the general population and occupy virtually every niche in society. Often ruthless, callous and completely devoid of empathy, they impose an incalculable toll on individuals and society. And science is increasingly learning that psychopathy may actually be a genetic disorder — one that could eventually be eliminated.

But what if it turns out that we actually need psychopaths?

As a term, psychopathy often means different things to different people. Part of the problem is that psychopathy is not a recognized clinical term, one that's defined within the DSM-IV. But this is starting to change. There's growing consensus among clinicians and neuroscientists that psychopathy does in fact exist as a meaningful and identifiable personality disorder. A growing community of experts are starting to use psychopathy as a clinical diagnosis.

Another part of the problem is that it's often used interchangeably with such terms as sociopathy and antisocial personality disorder (ASPD). While sociopathy is a rather vague term, ASPD does have a strict definition within the DSM-IV — but it's not the same same condition as psychopathy. ASPD is diagnosed based on behavioral patterns, while psychopathy includes behavior but also measurable cognitive, emotional, and neuropsychological differences from neurotypical people. And thanks to fMRI brain scans, neuroscientists are increasingly showing that there is a consistent and identifiable neurological basis for psychopathy.

In terms of definition, psychopathy is a personality disorder characterized by severe emotional dysfunction, especially a lack of empathy and remorse. Psychopaths exhibit consistent disregard for the feelings of others and the rules of society. They are completely unable to recognize such things as anger and fear in individuals, either based on facial expressions or verbal exclamations. In terms of behavioral traits, psychopaths are generally regarded as being callous, selfish, dishonest, arrogant, aggressive, impulsive, irresponsible, and hedonistic. At the same time, psychopaths often exhibit higher than average intelligence and a superficial kind of charm.

But clearly, given that nearly 2 in every 100 persons is a psychopath, they can't all be bad — otherwise society would have completely imploded by now. There's evidently more to this issue than meets the eye.

An underlying genetic basis

Scientists are increasingly finding a genetic basis to psychopathy. Work in genetics has revealed that the heritability coefficient for psychopathy is a shocking 50%. Psychopathy, it would appear, runs deeply in the family.

Moreover, neurologists are learning that psychopathy can manifest early in a person's life. There's an understandable reluctance to brand children as psychopaths, which is fair given the amount of stigma involved, and the fact that many children "act out" in age-appropriate ways. Consequently, therapists and researchers instead use the term "unemotional-callous" to describe what might actually be protopsychopathology.

Back in 2005, a twin study found that antisocial children could be classified into two groups: those who were influenced by both genetic and environmental factors, and those influenced by environmental factors alone. Of the two, the former group experienced the highest rankings of callous-unemotional traits.

But while genes may be a key factor, there's still plenty of room for environmental factors. It's thought that, while genetic factors may generally influence the development of psychopathy, the environment still affects the specific traits that predominate.

Psychologist Robert Hare, a leading expert on such matters, has argued that psychopathy may actually be adaptive. He has observed how many male psychopaths have a pattern of mating with and quickly abandoning women — and as a result, have a high fertility rate. His contention is that these children may inherit a predisposition to psychopathy.

And there appear to be physiological differences between psychopaths and everybody else — a recent study showed that the psychopathic brain has significantly less grey matter in the anterior rostral prefrontal cortex and temporal poles than the brains of both non-psychopathic offenders and non-offenders. These areas of the brain appear to be important for reading other people's emotions and intentions, and seem to be active when people think about moral behaviour.

Neuroscientists have also found that the amygdala is impaired in psychopaths. The amygdala is responsible for stimulus-reinforcement learning and responding to emotional expressions, particularly fearful expressions. It is also involved in the formation of both stimulus-punishment and stimulus-reward associations.

The psychopaths among us

At first blush, the estimate that 1 to 2 percent of all people are psychopaths seems astonishingly high. In a country like the United States, this implies that there are between 3 to 6 million psychopathic Americans. Psychopaths also make up roughly 15 to 25 percent of the prison population, and are responsible for the lion's share of brutal crimes and murders. And according to the neuroscientist Fabrice Jotterand, psychopathy affects 3 to 5 % of all CEOs.

But not all psychopaths are dangerous. Given the high prevalence of psychopathy in our gene pool, and given that many seem to fare rather well in society, it's fair to say that we run the risk of generalizing about this condition and pigeonholing all psychopaths as being inherently dangerous.

That said, it's not outrageous to suggest that psychopathy may eventually be branded as a genetic disorder — one that may be subject to prenatal screening or gene therapy. Genomics and the practice of preimplantation genetic diagnosis may eventually alert prospective parents, not to mention their fertility doctors, to the possibility that their offspring could be psychopathic. Genetic technologies may put prospective parents in a difficult position, if tests reveal that their future child has a high chance of being a psychopath.

This issue could get trickier if the government gets involved. According to an estimate by the neuroscientist Kent Kiehl, the national cost of psychopathy in the U.S. stands at $460 billion a year — roughly 10 times the cost of depression. The government could stand to save a lot of money, if it decides that psychopaths should never be born in the first place.

Robert Hare, co-author of Snakes in Suits, takes a hard-line when it comes to psychopaths, referring to them as "intraspecies predators." He argues that they lack the very qualities that allow humans to live in social harmony and is concerned about their ability to blend in, undetected, in a variety of surroundings, including corporate environments. By conceptualizing psychopaths as remorseless predators, he feels we can better understand what often appears to be senseless behavior.

Indeed, it may very well have to be the human toll that's considered. Psychopaths, given their indifference and often insatiable desires, can harm people in any number of ways, whether through physical violence or ruthlessness in the workplace. It's the continuing prospect of having psychopaths around in the general population that may eventually determine whether they should be filtered from the gene pool.

An important social role?

But a reality check is also in order. As already noted, not all psychopaths are violent. In fact, that's far from the case.

Psychopathy is not an all-or-nothing proposition. Like autism, it falls along a spectrum. The Hare Psychopathy Checklist, a standard inventory used in law enforcement, has a top score of 40. Psychopaths tend to get a bit scary when they score in the early 20s. A very demented and dangerous psychopath would score around a 30. As journalist Jon Ronson has noted, "There are absolutes in psychopathy and the main absolute is a literal absence of empathy. It's just not there. In higher-scoring psychopaths, what grows in the vacant field where that empathy should be is a joy in manipulating people, a lack of remorse, a lack of guilt. If you've got a little bit of empathy, you're kind of not a psychopath."

This is why Ronson and others feel that some psychopaths make for great CEOs. "I think the other positive traits for psychopaths in business is need for stimulation, proneness to boredom," Ronson told Forbes. "You want somebody who can't sit still, who's constantly thinking about how to do better things."

Kevin Dutton, the author of the upcoming book, The Wisdom of Psychopaths, agrees. He feels that psychopathy is an indelible component of the human fabric that extends well beyond the business world. Dutton feels that psychopaths have a lot of good things going for them. He argues that they are fearless, confident, charismatic, ruthless and focused -– qualities Dutton believes are tailor-made for success in 21st century society. Specifically, attributes like coolness under pressure and strong desire give rise to successful surgeons, firefighters, movie stars, and attorneys. Weed out psychopathy, argues Dutton, and you may lose some very important personality traits that help to create the greater whole that is humanity.

No easy answers

Clearly the issue of whether or not psychopathy should be wiped out is not as straightforward as it might appear. As geneticists have shown, there's an adaptive nature to psychopathy — and its prevalence may actually be on the rise. And there may be a very good reason for it in the human gene pool, one that contributes to a kind of neurodiversity that's socially beneficial.

Taking a step back, an overarching question that needs to be asked is one about end-goals. What's more important: changing someone's behavior, or changing a person's state of mind? A consequentialist would argue that it's behavior, and that it doesn't matter what a person thinks or what kinds of empathic impairments they might have — all that matters is how they act. Subsequently, an argument can be made that, if we can root out criminally harmful behavior, our task is done.

But as Robert Hare has argued, that may not be good enough. The absence of empathy, he argues — the very definition of a psychopath — will always result in malevolence.

That may very well be the case, but the truest expression of humanity is the ability to extend empathy towards others — even those incapable of mustering empathy themselves.